In 1996, 41 percent of adults with AIDS in the U.S. were black, exceeding for the first time the percentage that was non-Hispanic white. One reason for this disparity may be differences in the quality of healthcare that minorities receive. Studies of quality of healthcare disparities have tended to look at physician, patient, or site characteristics in isolation. Thus, little is known about the relative importance of these factors and how they interact to give rise to disparities in healthcare. Using cross-sectional data from a national survey of HIV patients, the proposed research will use hierarchical modeling to assess the impact of individual, clinical, and contextual factors on racial and ethnic disparities in HIV care. More specifically, it will estimate the impact of trust on adherence and assess any racial differences in trust; evaluate whether African Americans and whites receive care at sites that are systematically different in the quality of care they provide; and estimate the impact of contextual variables such as neighborhood race, education, and income on the quality of care provided by clinics, controlling for both individual and site effects. Results of the study will be useful to providers and policymakers dedicated to improving disparities in HIV care.